We've got two numbers: 3937 and 7602. Let's find their sum.

Step 1: We'll start by adding the digits 7 & 2 in column 1 and get 9.

Step 2: We'll start by adding the digits 3 & 0 in column 2 and get 3.

Step 3: We'll start by adding the digits 9 & 6 in column 3 and get 15.
We'll write down the last digit 5 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 3 & 7 in column 4 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

So, 3937 + 7602 = 11539.

